Electric piano.



H. K! SANDELL.

ELECTRIC PIANO.

APPLICATION FILED AUG-5,1911% RENEWED DEC. 30,1914.

I 1 1%8,7l9@ Patented Aug. 3, 1915.

4 SHEETSSHEE I.

H K. SANDELL. ELECTRIC PIANO APPLICATION FILED AUG-5, I913. RENEWED DEC. 30, 1914.

1,918,719, Patented Aug. 3, 1915.

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H. K. SANDEL'L.

ELECTRIC PIANO.

APPLICATION HLED AUG-5, 19I3. RENEWED DEC. 30,1914.

1,18,7193 Patented Aug. 3, 1915.

4 SHEETS-SHEET 3.

H. K. SANDELL.

ELECTRIC PIANO. APPLICATION FILED AIJGJJ, i913- REIIEWED DEC. 30,1914.

1, 148,7 1 0 Patente& Aug. 3, 1915.

4 SHEETS- SHEET 4.

NITED STATES PATENT OFFICE.

HENRY K. SANDELL, OF CHICAGO, ILLINOIS, ASSIGNOR TO MILLS NOVELTY COMPANY,

, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS. '7

ELECTRIC rmno.

Application filed August 5, 1913, Serial No. 783,131. Renewed December 30, 1914. Serial No. 879,804.

To all whom it may concern:

' Be it known that I, HENRY K. SANDELL, a

citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a new and useful Improvement in Electric Pianos, of which the following is a specification.

The primary ObJBCt of my invention is to simplify the mechanism of the piano-action, particularly that of the upright piano, although it is adaptable to all types of pianos.

'VVhile this improved action-has been immediately devised by me for use in automatically-played pianos, and particularly those that are operated electrically, it is not intended to be limited thereto, for it is equally serviceable for manual playing and it may be readily adapted for pneumatic operation. Inasmuch, however, as this action has been applied by me to an electricallyoperated piano of the upright type, it is so illustrated in the drawings and the following description of parts is confined'thereto.

In the accompanying drawings, Figure 1 is a view in vertical selectional elevation of an upright piano provided with my invention; Fig. 2is a broken planviewsregarded in the direction of the arrow on line 2, Fig. 1', and showing key-like electrical contactstrips for use in manually sounding the piano-strings,'as in tuning the instrument; Fig. 3 is' a view in vertical sectional elevation of the action, showing a hammer and damper in their normal positions relativev to a piano-string, and the solenoids for operating them; Fig. 4 is a similar View of the same, but showing the hammer in its striking relation to the string and the damper withdrawn therefrom; Fig. 5 is a broken section in perspective, showing a swinging shaft for withdrawing all the dampers at once fromthe strings, as is done by depressing the loud pedal in the ordinary manu- .ally-played piano; Fig. 6 is a view in side elevation of a solenoid-operated device for regulating the expression in playing the instrument; Fig. 7 is a section on the irregular line 77, Fig. 6; Fig. 8 is a section on line 8, Fig. 7, and 'Fig. 9 is a diagram of the electric circuit containing the mechanisms for operating the piano-action, the expression-means, and the swinging shaft.

All the hammers, andtheir dampers and operating mechanism are constructed alike and rear vertically-extending iron bars 10' and 11, forming pole-pieces, which are connected at their upper ends by a cross-bar 12, preferably of diamagnetic metal, having a forwardly and upwardly projecting curved finger 13 on its forward end. A11 upper solenoid 14 is supported in the bars 10 and 11, and comprises a brass tube 15 about which, between the pole-pieces, is a coil 16. The armature or core 17 inthe tube 15 is bored longitudinally and tipped on each end with a tubular plug 18 of soft rubber for rendering noiseless the working of the core; and a soft rubber buffer-sleeve 19 extends in the tube between the rearmost tip 18 and a tubular brass plug 20 in the rear end of the tube. A rod 21 extends through the tube 15 and core contained therein, being sup-, ported in the tips 18 to adapt it to be reciprocated independently of the core. On the forward end of the rod is/ fastened a hammer 22, with which is connected a wire spring 23 depending from the finger 13, to be put understress by the forward movement of the hammer for striking a pianostring 24 and quickly retract the hammer after it has made its stroke. hammer and forward tip 18 is confined about the rod a light spiral spring 25.

Below the solenoid 14 are supported in the vertical frame-bars two solenoids 26 and 31. The solenoid 26 comprises a brass tube 27 closed at its rear end by a vented plug 28, the tube containing a rubber-tipped armature or core 29' and being surrounded, like the tube 15, by a coil 30. The solenoid 31 also comprises a brass tube 32 supported like the tubes of the other solenoids, containing a rubber-tipped armature or core 33 and being likewise surrounded by a coil 34; and between a vented plug 35 at the rear end of the tube 32 and the core therein is confined a spiral spring 36. A stem 37 extends from the core 33 and carries on its forward end an ordinary string-damper '38, to be reciprocated relative to the string 24; and a stem 39 on the core 29 carries on its outer downwardly-bent end a head 40, through a perforation in which the stem 37 passes and is rigidly. fastened by a depending set-screw Between the 41, thus preventing axial turning of the core 33 and damper-carrying stem in moving. When the coils are energized, the advance of the.core 17 compresses the spring 25 until the inertia of the rod 21 is overcome, when that spring expands in the forward direction and quickly shoots the hammer against the string 24, and the momentum of the advancing hammer puts under stress the spring 23, causing the hammer to rebound and be retracted from the string. As the hammer strikes the piano-string, in order to permit proper vibration of the latter, the backward movement of the cores 29 and 33 retracts the damper 38; and when the coils 30 and 34 become deenergized, the spring 36, compressed by the backward movement of the core 33, as shown in Fig. 4, expands and returns the damper to its normal position as shownin Fig. 3. .The purpose of using two solenoids 30 and 34 is to get suflicient ampere-turns and enough power into the small space available, without danger of overheating the solenoid. By providing the two sol noids connected in series, greater magnetic power is obtained than by providing a single solenoid of the same size or diameter as that of the two solenoids.

As will be understood, the tendency of the windings is to bring coincident with their transverse centers those of the cores. The core 17 is set to bring its said center normally behind that of the coil 16 and the cores 29 and 33 are set to bring their centers normally ahead of those of the respective, coils 30 and 34. The core 17, in advancing, is carried by its momentum slightly in advance of the aforesaid centralized position, as shown in Fig. 4, but it is instantaneously retracted thereto by its coil, thereby releasing the spring 25, andpermitting the spring 23 to retract the stem 21 and hammer. In the same way, when the-cores 29 and 33 are centralized, in the sense referred to, after retracting the damper 38 they remain thus centralized, keeping the damper oil the string to permit it to vibrate, as long as the coils remain energized, this being governed by the length of the particular perforation in the traveling music-sheet; and when the coils are deenergized, which is not until after the core 17 has been restored to its aforesaid central position, the compressed spring 36 is thereby released to expand and return the damper to its position against the string.

A set of the described solenoids, including the frame,,a hammer and damper, is provided for each string.24, or set of strings of the same pitch. The frames carrying these mechanisms are rigidly connected in properly-spaced relation by an iron bar 42, of L- shape in cross-section, extending across and fastened to the frame-bars 12, and preferably divided and separated by insulation midway between its ends, as shown in Fig. 9. At each end of the bar 42 a bracket, like that shown at 43 in Fig. 1, projects from the face of the piano-frame. The bar 42 is supported at its ends on the upper arms of these brackets and is screwed, as represented at 44, to shoulders thereon. On the lower bracketarms is secured at its ends, to incline, as shown, a channeled bar 45, preferably of aluminum, and into which lead the cables (not shown) containing the electric wires for supplying current to the electrical mechanisms. This bar is faced with insulating material 46, and has a metal contact-strip 4 secured to its lower edge to project slightly. above the face of the insulation. Coincident with each hammer-carrying frame, a binding-post 48 is provided on the material 46 and has connected with it, as shown in Fig. 2, one end of the insulated wire 49 for supplying electric current to the adjacent coils, the opposite end of this wire, which leads from a coil 16, being connected with the bar 42.. Each binding-post 48 clamps a terminal 50 on a wire 49 against a spring contacttongue 51 fastened on the material 46 and normally out of contact at its lower end with the strip 47; and the tongues 51 are faced with insulating material 52, such as felt, to adapt them to be manipulated without shock. The tongues 51 are provided to be depressed by the fingers for closing the circuit to actuate the hammers, as hereinafter described, when tuning the piano.

A shaft 53, shown in Fig. 5 to be of general U-shape and cushioned, as with softrubber tubing 54, is pivotally hung at its ends on the brackets 43 to swing between them and bear at its cushioned portion backwardly against the row of set-screws 41, which thus form abutments on the stems 37 to be engaged by the shaft in swinging backwardly. An arm 55 extends from the shaft near one end thereof and is connected by an adjustable link 56 with a crank 57 on the rocking armature-shaft 58 (Fig. 1) of an oscillatory electric motor 58. This motor need involve no features of novelty, but may be of well-known construction and manner of operation, so that it does not require detailed description in the present connection. The particular type of motor conventionally indicated is that disclosed in my Patent No. 1,087,556, patented February 17 1914',

Means coiiperating with the described hammer-operating mechanism for automatically regulating loud and soft playing of the piano, or the expression in playing it,

are illustrated in Figs. 6, 7 and 8: A support is shown, consisting of a narrow fiat 1'ron bar 59-having pole-pieces 60, 61 and 62 rising from it at intervals, and vertical side-mem bers 63, .of insulating material, fastened to its opposite edges near one end of the bar,

at which rises a guide-bearing 64. On the cal position, a diaphragm-device comprising a vented cup 65 covered by aflexible metal diaphragm 66. A solenoid is supported on the bar and comprises a brass tube 67 supported in the pole-pieces thereon and surrounded,.between the pole-pieces 60 and 61, by a coil 68, and between the pole-pieces 61 and 62 by-a similar coil 69. A core 70, common to both of these coils, is confined to be reciprocated in the tube 67 and has a rodconnection 71 at one end with the center of the diaphragm; and a rod 72 extends from the opposite core-end through the guidebearing64. A frame 73, through which the rod 72 passes and to which it is fastened by a set-screw, works between the side-members 63 and has supported init outwardly springpressed contact-member's 4 to bear against the inner heated ends of wires 75 and 7 5' projecting through the side-members 63 and forming resistances. The reciprocating movements of the core 70 cause the resistances 75, 7 5 to be traversed b the contactmembers 74, for cutting in an out portions to produce softer and louder hammerstrokesagainst the piano-strings in playing. A light spiral spring 76 is confined about the rod 72 between the frame 73 and bearing 64, and a like spring 77 is similarl confined between thatbearing and a stop 8 adjustabl secured on the rod near its advanceen I I In Fig. 9, the entire mechanism hereinbefore'descrlbed is shown diagrammatically arranged in an electric circuit, including a contact-roller 79, over which a perforated music-sheet (not shown) is caused to travel to'. close the circuit at 1 branches thereof brushing through the sheet-perforations when they register with the brush ends of thesebranches. The circuit may be traced as follows: One side, a, of the line leads to A the roller 7 9, and has a branch a" leading to the bar 47. Theother side, 5, leads to thetube 67 of the expression-mechanism, and is continued, as wire 5 to thefmotor 58, from which extend wires 5 and b brushing the contact-roller. It will be understood that 1n this type of motor the field magnets are each provided with two opposite windings.

The wire 5 leads to the frame and is in series with the armature. The wire 5 leads from one winding ofthe field magnet and the wire 5 leads from the other winding thereof. Thus current over wires 5 b turns the armature in one direction, and

current over the wires 5 6 turns it in the oppos te direction. Wires 0 and 0', each brushing at one end against the contactroller, lead, respectively, to the coils 68 and 69, the return for which is over wire 7;. Wires 49 brush, each at one end, against the contact-roller, and each leads to a contacttongue 51 and, through a separate hammer and damper operating device, to the bar 42,

and return-wire b. .With electric current on the line and a perforated music-sheet traveling across the roller 7 9, the circuit is closed each time a brush makes'contact with the roller. through a perforation in the sheet, the perforations in which are suitably cut to produce the performance of a particular composition by properly working the pianoaction and regulating the loud and soft playing of the hammers. Thus, when a sheet-perforation registers with a brush on a certain wire 49, the respective solenoid 14 is energized to advance a hammer and the respective solenoids 28 and 31 are energized to retract a damper. The coil 68, for softer playing, or the coil 69, for louder playing, is energized either over the wire 0 or the wire 0. The formation of the bar 42 in two sections, insulated from each other, is desirable since it adapts each section to be controlled by a separate resistance. That is to say, if'the bar were continuous, instead of being formed, as shown, of the two sections insulated from each other, a single resistance for the continuous bar would, when a plurality of thehammers were actuated simultaneously, render the current too weak to work them; and by thus dividing the bar and providing a resistance for each section, the amount of current is always suificient to operateas many hammers as may be worked simultaneously. By energizing the coil 68, the core is attracted toward the right hand's'ide of Fig. 9, to out in resistance in or 75', and produce softer playing; and by energizing the coil 69, the core is attracted in the opposite direction to cut out resistance in one or the other of the resistances and produce louder playing. Reciprocation of the stem 71, under the movements of the core, vibrates the diaphragm toregulate or steadythe motions of the core, as would a dash-pot. This regulation is supplemented by the springs 76 and 77, since when the core and stem 72 are moved toward the left, in Fig.9, the spring 76 is compressed, to expand, upon the respective coil becoming deenergized, and quickly restore the core to its normal position; and when this movement is in the opposite direction, the spring 77 is compressed, to expand under the same condition of the respective coil, and quickly restore the core to its normal position. When a contact-tongue 51 is depressed against the strip 47, the circuit is closed over wire a, wire a, bar 47, tongue 51, through the action-magnets; and the return is the same as when a brush 49 contacts with the roller 79. When the wire I) brushes against the contact-roller, the armature of the motor 58 is turned to swin the shaft 53 backwardly against the row 0 setscrews 41 and retract all the dampers from the strings, to produce the same effect in playing as does depression of the loud pedal of the ordinary piano; and when the wire I) brushes against the contact-roller, the circuit is closed to. turn the armature in the opposite direction and restore the shaft 53 to its normal position, thereby permitting the springs 36, which were compressed by the action of the rock-shaft against the set-screws, to expand and advance the dampers against the strings. a I realize that considerable variation i possible in the details of construction thus specifically shown and described, and I do not intend by illustrating a single specific or preferred embodiment of my invention to be limited thereto; my intentlon being in the following claims to claim protection for all the novelty there may be in my invention as broadly as the state of the art will permit.

l/Vhat I claim as new and desire to secure by Letters Patent is 1 1. In a piano, a string, a solenoid provided with a reciprocable core, a hammer, stem and a hammer thereon movable independently of said core toward and from the string, and means on the stem between the hammer and core engaged by the core in its advance movement to impinge against the hammer and impel it against said string.

2.--In-a piano, a string, a solenoid provided with a reciprocable core, a hammer, stem and a hammer thereon movable independently of said core toward and from the string, and a spring interposed between the hammer and core to be compressed by the forward movement of the core and by its expansion strike the hammer against said string.

3. In a piano, a string, a solenoid provided with a reciprocable core, a hammer,

stem and a hammer thereon movable independently of said core toward and from the string, a spiral spring confined against the hammer in the path of the core' to be compressed by the forward movement of the core and by expansion advance the stem to strike the hammer against said string.

4. In a piano, a string, a solenoid provided with a tubular reciprocable core, a hammer, stem and a hammer thereon movable within' said core and independently thereof toward and from the string, a spiral spring confined about the stem between the hammer and core tobe compressed by the forward movement of the core and by expansion advance the stem to strike the hammer against said string.

5. In a piano, a string, a solenoid provided with a tubular reciprocable core, a'

hammer, stem and a hammer thereon movable within said core and independently thereof toward and from the string, a spiral spring confined about the stem between the hammer and core'to be compressed by the forward movement of the core and by expansion advance the stem to strike the hammer against said string, and a relativelystifl spring connected with the hammer to be put under stress by the advance movement of the stem and retract the stem by the recoil of said last-named spring. 7

6. In a piano, a string, a solenoid pro vided with a reciprocable core set with its transverse center normally behind that of the coil, a hammer, stem and a hammer thereon movable independently of said core toward and from the string, a spring interposed between the hammer and core to be compressed by the forward movement of the core and by its expansion strike the hammer against said string, a second solenoid-magnet having a reciprocable core set with its transverse center normally ahead of that of the coil, and a spring-pressed dampercarrying stem extending from said last named core. m

7 In a piano, the combination of a string, a frame having opposite pole-pieces, a solenoid having a-tube supported in the upper part of the frame in said pole-pieces, and a coil about and a tubular core within the tube, a hammer, a stem carrying the hammer confined in said core to be reciprocated independently thereof longitudinally in a direction transverse to the string, a spiral spring confined about the stem to be compressed by forward movement of the core and, by its expansion, advance the stem to strike the hammer against said string, -a

spring connected with the hammer to be put under stress byi the advance-movement of the stem and retract thestem by the recoil of said last-named spring, a second solenoid having a tube supported in the lower part of the frame, and a coil about 2 and a core within the tube, a spring behind the core in the lower tube, and a dampercarrying stem on the last-named core to be reciprooated longitudinally with relatlon to said piano-string, said cores being confined in the coils to be moved, by energizing the latter, simultaneously in relatively-opposite directions.

8. In a piano, the combination of a string,

a frame having opposite pole-pieces, a solenoid having a tube supported in the upper part of the frame in said pole-pleces, and a coil about and a tubular core within the tube, a hammer, a stem carrying the hammer confined in said core to be reciprocated j independently thereof longitudinally a direction transverseto the strmg, a splral spring confined about the stem to be compressed by forward movement of the core and, by its expansion, advance the stem to strike the hammer against said string, a second solenoid having a tube supported in the lower part of the frame in said polepieces and a coil about and a core within the tube, a spring behind the core in the lower tube, and a damper-carrying stem on the last-named. core to be reciprocated longitudinally and parallel with said hammerstem, and a third solenoid having a tube 10 supported in the frame in said pole-pieces and connected with said damper-carrymg.

stem.

-HENRY K. SANDELL.

In presence of- L. HEISLAR, A. J. FLoYD. 

